Bag forming tube and method of forming and accumulating the same



May 8, 1962 H. H. WEBER 3,033,257

BAG FORMING TUBE AND METHOD OF FORMING AND AC-CUMULATING THE SAME Filed Aug. 21, 1957 2 Sheets-Sheet 1 Erg-1 3 May 8, 1962 H. H. WEBER EAG EDRA/ENG TUBE AND METHOD oF EDRA/ENG AND AccuA/AULATTNG THE SAME 2 Sheets-Sheet 2 Filed Aug. 21, 1957 /gq ww' wf Afwa- Sllf 3,033,257 BAG FRMING TUBE AND METHOD DF FORM- ING AND AQCUMULATING THE SAME Herbert H. Weber, Sheboygan, Wis., assignor to H. G. Weber and Company, Inc. Filed Aug. 21, 1957, Ser. No. 679,384 8 Claims. (Cl. 15b-1) The present invention relates to improvements in bag constructions and methods for manufacturing bags.

More specifically, the invention relates to a bag construction and method of forming the bag wherein a series of bags are formed from a long length of bag material without waste of the material. The material is preferably formed of a thermoplastic, such as a polyethylene or vinyl polymer that is adapted to form a exible and relatively transparent bag of an inexpensive construction. In one form a length of tubular material which may be seamless is employed. In another form fiat material will be used. In this instance, the length of flat material is prepared with one or both edges turned inwardly toward the center to overlie the center portion of the material, thus forming a two layer tubular length of bag material.

The tubular material or flat folded material is formed into a succession of bags by forming transverse seams across the material which are partially severed by interrupted slit lines. One or a pair of bags are formed across a supply length of material and the bags are separated by tearing them from the supply.

The present invention contemplates forming a supply of preformed bags which can be individually separated from the length when individual bags are needed and used. Transverse seams are formed across the length of tubular material at spaced intervals equal to the width of bag to be formed.

In one form a seam is made by separating the material in spaced slits and the layers at the sides of the slits joined to form a seam. Between the ends of the slits spot welds wider than the slits form a continuation of the seams which are at the sides of the slits.

In another form uniform seams are made and are cut down their center with elongated interrupted slits. The seam may be interrupted in the area between the ends of the slits in order that the seams of the bags may open when the bags are iilled to provide a vented bag. The seams also may be continuous between the ends of the slits to form a continuous seam down the sides of the bags.

Accordingly, it is an object of the present invention to provide an improved bag construction wherein a plurality of bags may be manufactured and retained as an integral part of an elongated supply length of bag material.

Another object of the invention is to provide a bag construction wherein preformed bags remain in an attached state to a supply length of a plurality of bags, and the individual bags may be readily and simply removed from the end of the supply as they are needed.

Another object of the invention is to provide an improved bag construction and a method of making bags which effects a saving in operations and in material and obtains a readily available easily handled supply of bags.

Another object is to form a supply of bags attached to each other at spaced intervals along side seams wherein the attached portions may be torn without danger of damaging the bag side seam.

Another object of the invention is to provide an improved bag construction for vented bags.

A further object of the invention is to provide an improved method for making bags from lengths of thermoplastic material.

Other objects and advantages will become more apparent with the teaching of the principles of the inven- 3,@33257 patented May 8, 1962 ice tion in the disclosure of the preferred embodiments thereof in the following specification, claims and drawings, in which:

FIGURE 1 is a plan view illustrating a part of a supply length of bag material and showing the bag construction and the method of making the bags of the present invention;

FIGURE 2 is a plan view of a part of a supply length of bag material illustrating another bag construction and method of making the bags; y

4FIGURE 3 is a plan view taken from the bottom of a device for use in connection with forming the bags;

FIGURE 4 is a vertical sectional View taken along line IV-IV of FIGURE 1 illustrating the steps of seaming and slitting;

FIGURE 5 is an end view of a roll of bag material shown to illustrate a manner of storing finished bags;

FIGURE 6 is a side elevational view showing the position of a length of bag material in another form which may be used for storing bags;

FIGURE 7 is an illustration of a length of bag material inthe form of the invention wherein the supply material is originally tubular in shape; f Y

FIGURE 8 is another illustration of a length of bag material showing one form of the laterally extending seams;

FIGURE 9 is an enlarged sectional view taken along line IX-IX of FIGURE 8 illustrating the appearance of the slit with the seams at the side of the slit; v

FIGURE l0 is a perspective view showing one form of a seaming device;

FIGURE l1 is a perspective view illustrating another form of seaming device;

FIGURE 12 is a vertical sectional view taken through the seaming devices and a bag illustrating the operation of the pair of seaming devices forming a seam across the bag; and,

FIGURE 13 is a plan view of a supply length of material illustrating still another form of the lateral seam.

In the figures of the drawings, various forms of seams which may be made in accordance with the principles of the invention are illustrated. It will be understood that the bags are formed from a length of supply material which may be either flat in its original for-m or tubular. If tubular, it may be slit longitudinally in order to be formed and folded in accordance with the invention. The various forms will be discussed in the order in which the drawings appear with the preferred forms being illustratedy as the nal bag supply material in FIGURES 8 and 13.

Referring to FIGURE l, a length of bag material 10 is shown in plan view to illustrate the method of forming bags therefrom. In this form, bag material originally is a at layer of thermoplastic material, such as a vinyl polymer, polyethylene, or other suitable plastic that is heat sealable and is adapted to form a flexible and relatively transparent sheet of material for the formation of inexpensive bags or containers.

The flat layer of material 10 is rst doubled in a lengthwise direction with the first edge 12 being brought over on top of the material toward a second edge 14, but short of the second edge to form the arrangement shown in FIGURE l. This will leave an area 16 of material between the two edges 12 and 14 which will be located at the top of the bag and will be an extension of the rear side wall of the finished bag. The rear side Wall of the bag will be formed by a lower layer 18 of the doubled material and the front side wall will be formed by an upper layer 2t) of the doubled material.

In accordance with the method of the present invention, the bag areas are next dened by forming transversely extending welded seams, such as shown at 22 and 24 extending across the bag and joining the layers 13 and 20 together. The seam area 22 extends from its edge 26 to its other edge 28. Since the seams are identical, only seam 22 will be described in detail.

The seam area is next slit by the formation of a series of elongated cuts or slits 30, 32 and 34 which are spaced from the edges 26 and 28 ofthe seam, and are preferably centrally located between the edges 26 and 2S. The slits are each separated at their ends by a continuous or unslit length of material with the slits 30 and 32 separated by the unslit area 36, and the slits 32 and 34 separated by the unslit area 38. Further, end slits 3G and 34 do not extend completely to the edges of the material. The slit 34 has an unslit area 40 between its end and the edge 14 of the material. The slit 30 has an unslit area 41 between its end and the doubled edge 40a of the material.

Thus, when a bag, such as shown by the area 42 is removed from a supply length 44 of the material, the user grips the bag, pulling it away from the supply length 44. The slits will, of course, immediately separate and increased pressure will cause the unslit areas 36, 38, 40 and 41 to tear, thus releasing the bag.

The transverse seam 22 will have an area 46 on one side of the series of slits which will serve the bag 42. The area 48 of the seam on the other side of the slits will serve a succeeding bag 50.

Although the formation of the seam has been shown and described with material folded as shown in FIGURE 1, it will be understood that the seam may be made using the same construction with tubular material.

As an example of a mechanism used in practicing the method of the invention, a sealing bar 52, FIGURES 1 and 3, is employed. The bar may be applied manually or may be applied by mechanical means such as by being mounted on the surface of a roller which will rotate as the length 44 of material is moved forwardly.

The bar 52 acts as a carrier for the seam-forming and slitting means and carries a series of slitting knives such as 54 and 56 on its lower surface 58. As shown in FIG- URE 4, illustrated by the knife 54, the knife has a V- shape with a sharp lower straight elongated edge 60. When the knife 54, which is heated, forces its way through the upper and lower layers and 18 of the material to sever them, the knife is pressed against the material. The material is shown resting on an upper surface of a table 62 or suitable support. As many knife lengths are provided for the bar 52 as there are slits across the material.

While the material is being cut, seaming surfaces 64 and 66 press against the material to form elongated seam areas 68 and 70. The seaming surfaces 64 and 66, as r shown in FIGURE 3, are at elongated areas extending on each side of the cutting knives 54 and 56. The seaming surfaces are continuous, extending across between the ends 72 and 74 of the knives '56 and 54 and also across and beyond the end 76 of the knife 54. This insures that the seam will be continuous completely across the length of material, although the slit portions will be intermittent.

Thus, in effect, a spot weld will be formed at the locations 36, 38, 40 and 41 at the ends of the slit portions. In some instances, it may be desired to make a special and separate spot weld at the locations between the slits. When the individual bags are pulled from the length of bag material, the bags will freely separate along the slits and the welded areas between the slits, which may be spot welds, must tear. The tearing will generally follow the line of slits so that the bags will separate substantially along a straight line between the slits.

When the bar 52 is brought into sealing position, as shown in FIGURE l, the edges 60 of the knives S4 or 56 cut through the layers of material forming the slits across the material. The bar is heated and is shown as having a built-in electrical heating element 80, which maintains the length of the bar at a uniform temperature which is suilicient to soften and weld the thermoplastic as the bar is applied thereto without causing it to burn.

As illustrated in FGURE 4, the at sealing surfaces 64 and 66 press down at the sides of the slit lines to soften the material and cause a weld to join the layers of the material, as indicated by the areas 68 and 70. The bar S2 is held in place for a short period of time and then removed.

The supply lengths of bags joined which are interconnected `by the continuous spots between the severed lines, may be wound into a cylindrical roll 82, as shown in FIGURE, 5, supported on an axis 84 whereby the roll may rotate as individual bags are pulled off the roll.

Another manner of storing the bags in their continuous form is illustrated in FIGURE 6, wherein the material is formed into an accordion-folded stack 86. The folds, such as 88 and 90 may be formed at any location along the material, or may be formed along the slits where the material will assume a sharp fold and where a full layer of the stack is removed each time an individual bag is torn from the end of the supply.

In the embodiment illustrated in FIGURE 2, a length 92 of bag material is supplied and is prepared so that two bags will be formed with each section that is removed from the end of the material supply.

The two longitudinal edges 94 and 96 of the originally at single layer of material are folded inwardly toward the center 98 and laid upon the material so as to be just short of reaching the center. The edge 94 draws an upper layer Miti of material over a lower layer 1552 of material to form a front and a rear wall of the bags which are manufactured from the material. The edge 96 brings an upper layer 104 over a lower layer 106 to form the front and rear wall of the bags which are formed from one-half of the width of the material.

Transverse seams such as 108 and 110, and 112 are formed laterally across the folded material at spaced intervals spaced in accordance with the width of the bag desired. Each of the seams is the same as seam 108 which will be described in detail. Seam 108 extends completely across the folded material. Between the edges 116 and 118 of the seam 10S are a series of separated slits 120, 122, 124, 126, 128 and 130. At the end of the slits, and between the ends of each of the slits is a continuous welded area which, in effect, forms a spot weld between the slits with these welded unslit areas `being illustrated at 132, 134,

s 136, 13S, 140, 142 and 144.

The seam 108 combined with the next succeeding seam forms a pair of bags 146 and 14S which are separated at their tops by a longitudinal slit 15G. The longitudinal slit is part of a series of slits extending down the center line 98 between the rows of bags. These longitudinal slits are separated by areas of continuous material which are unslit, as shown at 133, 152 and 154. These areas of material prevent the length of supply material from separating down the center and permit separating the laterally opposite bags such as 146 und 143.

The seams 10S, 110 and 112, with the intermediate slits between their edges, may be formed by a bar similar to FIGURE 3. The seam line down the center 98 ofthe material also may be formed by a bar with intermediate cutting edges, but this bar will not have sealing surfaces at the sides of the cutting edges.

in some instances it appears desirable to provide a bag which has air vents. This may lie accomplished by providing special openings in the `bag walls, and in the present invention is accomplished in one form simultaneously with forming the bags.

For the formation of vented bags, in the arrangement of the bag supply material of FIGURE l, the areas 36, 33 and 4i between the ends of the slit lines will be left unseat-ned. Thus, although the seam sides 46 and 48 will join the layers of material on each side of the slits, they will extend only to the ends of the slits. The areas at the ends of the slits will be unseamed so that when bag 42 is separated from the supply end, its upper and lower walls 20 and 18 will be free to separate at the locations which were at the ends of the slits. The walls in separating rwill form vent holes to let the air into the bag. These ventholes, will, of course, be present in both sides of the bag, and each bag will thus be provided with vent holes.

In the bag of FIGURE 2, the areas 132, 134, 136, 140, 142 and 144 also will be unseamed. The walls of the bags will thus be free to separate in these locations to ventilata the contents thereof.

In making these vented bags, a sealing bar similar to the bar 52 may be employed. However, instead of the seeming surfaces 64 and 66 being continuous, the areas, such as 78, between the ends of the slit lines, will be interrupted. This can be chieved by providing an area of heat insulation at 78 or making the seaming surface discontinuous at this area. Thus, when the seam-ing tool 52 is applied transversely across the supply of material, only the seaming surfaces will seam the upper and lower layers of the bags and no seam will be formed at the ends of the slits.

As a summary of the method of forming the bags of FIGURE l, the supply of material 18 is doubled by bringing the edge 12 over the top of the material short of the outer edge 14. This brings the layer 28 over the layer 18, and these layers are welded to each other along laterally extending seams by placing a Welding and cutting bar 52 over the material at spaced intervals.

Seam 22, which is exemplary of the other seams, has an area in which the upper area is sealed to the' lower layer by fusion of the thermoplastic material. Between the edges 26 and 28 of the seam a series of interrupted slits 38, 32 and 34 are formed. These slits easily permit the separation of the bag from the end of the supply material by tearing the continuous areas 36, 38, 48 and 41 at the ends of the slits.

In the form of FIGURE 2, the opposing edges 94 and 96 of the length of material 92 are brough toward the center and a series of intermittent slits are formed down the center or" the material. The slits are separated by areas 138, 152 and 154 which Will be at the corners of the individual bags 146 and 148. Twin bags are formed at each side of the material by each laterally extending seam 188, 118 and 112, which extends completely across the material. Each seam has a series of intermittent slits centrally located between its edges with continuous areas such as 132, 134, 136, 138, 140, 142 and 144 at the ends of the slits. These continuous areas are torn when the individual bags are pulled from the supply of material which is maintained such as in `a roll 82 of FIGURE 5, or an accordion-folded stack 86.

In forming the vented bags, a method similar to that shown in FIGURES l and 2 is employed. The seams which extend on each side of the slits are, however, discontinued in the areas between the slit lines so that when the individual bags are moved from the supply of material their layers will ybe permitted to separate and form vent openings in the location where the layers are unseamed.

As illustrated in FIGURE 7, the bags may be formed from a continuous length 168 of tubular material. Thermoplastic material such as polyethylene is furnished as a stock supply item from manufacturers, being produced by them by extrusion methods and being obtainable at relatively inexpensive costs. The length of tubing 160 may be utilized in Various forms 4but is shown as being cut along the center along a line 162 to separate the tubular material into two sections. The sections may then be used as they are illustrated in FIGURE 7 or they may be arranged with each of the sections 164 and 166 folded as illustrated by the supply length 168 of FIGURE 8.

In this supply length of FIGURE 8, one of the edges 178 is drawn downwardly from the other edge 174 to provide a iiap area 176 for the bag.

The supply length 168 is formed with a plurality of laterally extending seams such as shown at 178 and 180. The seams 178 and 180 are spaced in accordance with 4are formed simultaneously.

plished by engaging the layers of material from one or 6 the width ot' the bag desired. The seam 178 will then form an edge for each of the adjacent bags 182 and 184 n and the seam 180 will form a seam for the other side of bag 184 and for la succeeding bag 186.

The seams 178 and 180 comprise discontinuous or intermittent slits such as 188, i190, 192 and 194 for the seam 178. Since seam 180v is identical with seam 178, only the seam 178 need be described.

The slits are separated by unsearned spaces between the ends of the slits and between the ends of the last slits and the top and bottom edges 174 and 196 of the bag respectively. The unseamed areas at the end of the slits, moving from the bottom to the top ofthe bag, are shown at 198, 200, 282, 284 and 286. These unsearned areas will provide vent holes in the side of the bag when the bags are torn from the supply.

The slit construction, as illustrated in FIGURE 9, consists of an elongated opening 288 with plastic bead seals 21() and 212 on each side. The bead 210 joins an upper layer 214 and a lower layer 216 of the bag 218. The bead 212`joins the upper layer 220 and the lower layer 222 at their edges to form the seam for the edge of bag 224. Thus the bags 224 and 218 will separate easily when a longitudinal pull is applied to bag 224 and each of the slits will spread, with the material between the slits tearing.

The slits, and the bead seals on each side of the slit, The formation is accom# both sides with a narrow heated surface.

For this purpose, a slit and seal forming series of members are shown at 226, 228, 230 and 232. These members are mounted on a support bar 234 to which they are integrally attached in linear alignment with spaces 236, 238 and 240 therebetween.

The slit and seam forming elements are heated by a heating element 242 embedded in the carrier bar 234.

This heating element brings them to a temperature where in the thermoplastic bag material is quickly melted to form the plastic bead seals on each side but they are not brought to a temperature wherein a danger of a conllagration exists.

The bar 234 is arranged with the slit and bead forming elements facing downwardly and applied to the layers of bag materials transversely yacross the supply length at the proper spaced intervals. If desired, as shown in FIG- URE 12, opposed members may be brought together so that they meet and the bag material is melted from both surfaces at the same time.

In FIGURE l2 an upper member 244 is brought dow-n against the upper layer 246 of material and a lower member 296 is brought upwardly against the lower layer 250 of material. The member 244 has a material engaging slit and bea-d forming member 270 which forms an inter-v then employed using the sealing element illustrated inv FIGURE ll.

In FIGURE 13 a length of supply material 277 is formed with the upper layer 278 folded over the lower layer 280 to a position short of the upper edge 282 of the lower layer to form a bag closing flap 284. Seams 286 and 288 are formed laterally across the supply of Vmaterial at distances spaced the desired distance of the width of a bag 298. The seams complete the edges of the bag 2.9i) joining the upper and lower layers and seam 286 also completes the edge of a bag 292 and seam 288 completes the edge of a bag 294. Y v v The bags are again formed with a plurality of elongated linearly aligned separated slits such as shown at 296, 298, 300 and 362 for the seam 286. The seam 286 is of a construction identical to seam 288 and, therefore, only one seam need be described.

The slits are again formed with bead seams on either side to join the edges of the bags.

Between the ends of the slits, spot welds such as 304, 336, 30S, 310 and 312 are formed. The spot welds are shown as being rectangular in shape and are seals which join the upper and lower layers of bag material over the area indicated.

When the bag 292, for example, is pulled from the bag supply, the bags will immediately separate along the slits and as the pressure is increased will tear across the sealed areas 304, 306, 3658, 310 and 312. Since the bags may tear irregularly in this area and since a continuous seal on the side of the bag is desired without a break, the seal area between the slits is wider than the seals at the side of the slits. Thus, even if a jagged tear is produced, there will still be seam material to close the layers of the bag.

The slits are again provided by ridges 314, 316, 318 and 329 mounted to project from a carrying bar 322. The bar is against provided with a heating element 324 to impart heat to the slit and bead seal forming elements. Between the ends of the elements are rectangular at sealing areas 325, 328 and 33). These hat elements are arranged to engage the bag at the same time as the slit forming elements and will form the spot weld areas be tween the ends of the slits. Although this is the preferred arrangement for forming the seam, in some instances it may be feasible to apply the spot welds at a time after the slits and the bead seals on each side of the slits are formed.

Thus, it will be seen that I have provided an improved bag construction with a mechanism and method of forming the construction which is well adapted to inexpensively manufacturing a large number of bags and which meets the objectives and advantages hereinbefore set forth. The method may be used on continuous sheets of plastic, or a tubular length formed of material such as polyethylene, which is obtained in roll form from the manufacturer. The bags may be made simply by rolling the material off the roll and reforming it in another supply roll. The supply roll contains the individual bags which are potentially ready for use. The user, thus can keep an entire roll or stack of the bags for his use tearing off the individual bags from the roll as they are needed. Thus, the bags themselves form a compact storage unit and repacking of the bags is not necessary during manufacture. These and other savings in time and material are apparent from the improved construction and method disclosed herein.

I have, in the drawings and specification, presented a detailed disclosure of the preferred embodiments of my invention, but it is to be understood that l do not intend to limit the invention to the specific forms disclosed, but intend to cover all modifications, changes and alternative constructions and methods falling within the scope of the principles taught by my invention.

I claim as my invention:

l. A bag construction comprising a length of bag material formed of a plurality of layers, a seam extending across the material and joining the layers of material to complete the seam for the edges of bags taken from the length of material, intermittent unjoined areas intersecting the seam operative to form vent openings in the nished bag, and slits along said seam between the edges thereof and terminating at said unjoined areas so that the layers of the bags separate along the slits with a portion of each side of the seam serving adjacent bags and the bags tearing apart at said unjoined areas.

2. A bag construction comprising a length of plastic bag material formed of a plurality of layers, said layers joined at least at one edge of said length to form an edge for bags to be removed from` the length of material, a plurality of rows of slits extending endwise laterally across the width of bag material and formed through each of the layers with said rows located at intervals along the length of the lbag material, the slits in each row being spaced from each other with spaces between their ends, and plastic weld beads extending along both edges for the length of each of the slits using a minimum of material and joining the layers of bag material at the edges of the slits with the layers of material immediately outside of said beads being freely separable so that beads at each side of the slits will serve to form the side edges of adjacent bags when individual bags are removed from the length of bag material.

3. A bag construction comprising a length of bag material formed of a plurality of layers, seams extending across the material and joining the layers of material to complete the seams for the edges of bags taken from the length of material, intermittent unjoined areas interrupting the seams to leave joined lengths therebetween and to form vent openings in the finished bags, and lines of severed material extending along the joined lengths of the seams and between the edges thereof so that bags may be separated from the lengths of material and so that the joined lengths form seams for the bags.

4. The method of forming a bag from opposed layers of bag material which comprises the steps of joining the layers of material along seam lengths and leaving spaced areas between the ends of the seam lengths where the layers are unjoined, and cutting the material along lines intermediate the edges of the seam lengths so that bags may be separated from a length of bag material by separation along said lines and by tearing in said spaced areas, the opposed layers of bags being separable in said spaced areas where the layers are unjoined and the joined layers along the seam lengths forming the connecting edges for the bags.

5. A bag construction comprising a length of plastic bag material formed of a plurality of layers, said layers joined at least at one edge of said length to form an edge for bags to be removed from the length of material, a plurality of rows of slits extending endwise laterally across the width of bag material and formed through each of the layers with said rows located at intervals along the length of the bag material, the slits in each row being spaced from each other with spaces between their ends, plastic Weld beads extending along both edges for the length of each of the slits using a minimum of material and joining the layers of bag material at the edges of the slits with the layers of material immediately outside of said beads being freely separable so that beads at each side of the slits will serve to form the side edges of adjacent bags when individual bags are removed from the length of bag material, and areas of said layers joined together between the ends of said slits in said spaces.

6. A bag construction comprising a length of plastic bag material formed of a plurality of layers, said layers joined at least at one edge of said length to form an edge for bags to be removed from the length of material, a plurality of rows of slits extending endwise laterally across the width of bag material and formed through each of the layers with said rows located at intervals along the length of the bag material, the slits in each row being spaced from each other with spaces between their ends, plastic weld beads extending along both edges for the length of each of the slits using a minimum of material and joining the layers of bag material at the edges of the slits with the layers of material immediately outside of said beads being freely separable so that beads at each side of the slits will serve to form the side edges of adjacent bags when individual bags are removed from the length of bag material, and welds joining the layers together in said spaces between the ends of the slits in an area extending laterally beyond the edges of the weld beads.

7. A bag construction comprising a length of plastic bag material formed of a plurality of layers, said layers joined at least at one edge of said length to form an edge for bags to be removed from the length of material, a plurality of rows of slits extending endwise laterally across the width of bag material and formed through each of the layers with said rowsfl'ocated at intervals along the length oi the bag material, the slits in each row being spaced from each other with spaces between their ends, plastic Weld beads extending along both edges yfor the length of each of the slits using a minimum of material and joining the layers of bag material at the edges of the slits with the layers of material immediately outside of said beads being freely separable so that beads at each side of the slits Will serve to form the side edges of adjacent bags when individual 'bags are removed from the length of bag material, and spot welds in said spaces between the ends of said slits joining the layers between the slits.

8. A bag construction comprising a length of plastic bag material formed of a plurality of layers, said layers joined at least at one edge of said length to form an edge for bags to be removed from the length of material, a pluraiity of rows of slits extending endwise laterally across the width of `bag material and formed througheach of the layers with said rows located at intervals along the length ol the bag material, the slits in each row being spaced from each other with spaces between their ends, plastic weld beads extending along both edges for the length of each ofthe slits using a minimum of material and joining the layers of Ibag material at the edges of the slits with the layers of material immediately outside of said beads being freely separable so that beads at each side `off the slits will serve to -lform the side edges of adjacent bags when individual bags are removed from the length of bag material, and welds joining the layers together in said spaces between the ends of the slits and extending to join said weld beads so that the seam at the sides of the bag will be formed of said weld beads with the welds therebetween.

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